The nature of the human T cell response to the cancer antigen 5T4 is determined by the balance of regulatory and inflammatory T cells of the same antigen-specificity: implications for vaccine design

The oncofoetal antigen 5T4 is a promising T cell target in the context of colorectal cancer, as demonstrated by a recent clinical study where 5T4-specific T cell responses, induced by vaccination or cyclophosphamide, were associated with a significantly prolonged survival of patients with metastatic disease. Whilst Th1-type (IFN-γ+) responses specific to 5T4, and other oncofoetal antigens, are often readily detectable in early stage CRC patients and healthy donors, their activity is suppressed as the cancer progresses by CD4+CD25hiFoxp3+ regulatory T cells (Treg) which contribute to the immunosuppressive environment conducive to tumour growth. This study mapped the fine specificity of Th1 and Treg cell responses to the 5T4 protein. Surprisingly, both immunogenic peptides and those recognised by Tregs clustered in the same HLA-DR transcending epitope-rich hotspots within the 5T4 protein. Similarly, regions of low Th1-cell immunogenicity also did not contain peptides capable of stimulating Tregs, further supporting the notion that Treg and Th1 cells recognise the same peptides. Understanding the rules which govern the balance of Th1 and Treg cells responding to a given peptide specificity is, therefore, of fundamental importance to designing strategies for manipulating the balance in favour of Th1 cells, and thus the most effective anti-cancer T cell responses.

A combination of electrochemotherapy, gene electrotransfer of plasmid encoding canine IL-12 and cytoreductive surgery in the treatment of canine oral malignant melanoma

The aim of this study was to evaluate the safety and efficacy of the combination of electrochemotherapy (ECT) with bleomycin and gene electrotransfer (GET) of plasmid encoding canine interleukin 12 (IL-12) for the treatment of canine oral malignant melanoma (OMM). Our focus was to determine the effect of the treatment on achieving local tumor control and stimulation of an antitumor immune response. Nine dogs with histologically confirmed OMM stage I to III were included in a prospective, non-randomized study. The dogs were treated with a combination of cytoreductive surgery, ECT and IL-12 GET, which was repeated up to five times, depending on the clinical response to the treatment, evaluated according to the follow-up protocol (7, 14 and 28 days after, the last treatment). One month after treatment, the objective response (OR) rate was 67% (6/9). Median survival time (MST) was 6 months and, even though the disease progressed in 8/9 patients at the end of the observation period (2 to 22 months), four animals were euthanized due to tumor-unrelated reasons. In addition, we observed a decline in the percentage of regulatory T cells (Treg) in the peripheral blood in the course of the treatment, which could be attributed to a systemic antitumor response to IL-12 GET. The results of this study suggest that a combination of ECT and IL-12 GET may be beneficial for dogs with OMM, especially when other treatment approaches are not acceptable due to their invasiveness or cost.

Immunomodulatory Effects of Human Adipose Tissue-derived Mesenchymal Stem Cells on T Cell Subsets in Patients with Rheumatoid Arthritis

Adipose-derived mesenchymal stem cells (Ad-MSCs) have been reported to suppress the effector T cell responses and have beneficial effects on various immune disorders, like rheumatoid arthritis (RA). This study was designed to investigate the effects of co-cultured Ad-MSCs on peripheral blood mononuclear cells (PBMCs) of RA patients and healthy individuals, through assessing transcription factors of T cell subsets. PBMCs from RA patients and healthy donors were co-cultured with Ad-MSCs with or without Phytohaemagglutinin (PHA). The quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of T-box 21 (T-bet), GATA-binding protein-3 (GATA3), retinoid-related orphan receptor γt (ROR-γt) and forkhead box P3 (Foxp3). Based on the results, Ad-MSCs greatly upregulated Th2 and Treg cell transcription factors, i.e., GATA3 and Foxp3 (p<0.05), and downregulated Th1 and Th17 transcription factors, i.e., T-bet and RORγt (p<0.05). These results demonstrate that Ad-MSCs can result in an immunosuppressive environment through inhibition of pro-inflammatory T cells and induction of T cells with a regulatory phenotype. Therefore, they might have important clinical implications for inflammatory and autoimmune diseases such as RA.

Characterization of Regulatory T Cells in Preterm and Term Infants

Our study aimed to study regulatory T cells (Tregs) and their expression of CD45RA, HLA-DR, and CD39 in preterm and full-term infants. In an observational study, we used a three-color flow cytometry for determination of Tregs and their expression of CD45RA, HLA-DR, and CD39 in preterm and full-term infants. The percentages of CD4⁺CD25^+highFoxp3⁺, CD39⁺ Tregs, HLA-DR⁺ Tregs and the expression of Foxp3⁺ in CD4⁺CD25^+highFoxp3 Tregs cells were significantly lower in neonates when compared to healthy adult controls. The levels of naïve resting Tregs (CD45RA⁺Tregs) were significantly higher in neonates than controls. The percentages of CD4⁺CD25^+highFoxp3⁺Tregs, total CD4⁺CD25⁺ and CD4⁺CD25^+high were significantly higher in preterm infants when compared to the full-term group. Moreover, CD45RA⁺Tregs were significantly higher in preterm than in term infants. We found significant inverse correlations between the gestational age and the levels of both Tregs (r = - 0.395, p = 0.017) and CD45RA⁺Tregs (r = - 0.422, p = 0.010). Relative to full-term, the frequencies, and phenotypes of Tregs were affected by prematurity. A larger longitudinal study with a sufficient number of newborns is needed to investigate the Treg pool of term and preterm infants thoroughly and to explore the association between the Treg pool and clinical variables.

Stromal interleukin-33 promotes regulatory T cell-mediated immunosuppression in head and neck squamous cell carcinoma and correlates with poor prognosis

Regulatory T cells (Tregs) mediate immunosuppressive signals that can contribute to the progression of head and neck squamous cell carcinoma (HNSCC). Interleukin-33 (IL-33) is defined as an 'alarmin', an endogenous factor that is expressed during tissue and cell damage, which has been shown to promote Treg proliferation in non-lymphoid organs. However, the interaction between IL-33 and Tregs in the HNSCC tumor microenvironment remains uncertain. In this study, we examined IL-33+ and Foxp3+ cells by immunohistochemistry in 68 laryngeal squamous cell cancer patients, followed by functional analysis of IL-33 in Tregs. In addition, the suppressive function of Tregs was assessed by cell proliferation assays. The level of stromal IL-33 was significantly upregulated in advanced versus early stage HNSCC patients and positively correlated with Foxp3+ Treg infiltration as well as a poor prognosis. ST2 is regarded as the only receptor of IL-33. Infiltrated ST2-expressing Tregs were responsive to IL-33, and the percentage of Tregs was increased upon IL-33 stimulation. Functional investigation demonstrated that IL-33 increased the proportion of Foxp3+GATA3+ Tregs and improved the suppressive functions of Tregs by inducing IL-10 and TGF-β1 as well as decreasing the proliferation of responder T cells. Blockade of ST2 abrogated the immunosuppression caused by IL-33. Our data demonstrate that stromal IL-33 both expands the Treg population and enhances their functions in the tumor microenvironment. Furthermore, stromal IL-33 has prognostic value for tumor progression. Thus, stromal IL-33 is a potential target for future HNSCC immunotherapy.

Foxp3+ regulatory T cells expression in neuromyelitis optica spectrum disorders

BACKGROUND

Alterations in the frequency or function of regulatory T cells (Tregs), which play a critical role in the maintenance of peripheral immune tolerance, are known to be involved in the pathogenesis of several autoimmune diseases. Neuromyelitis optica spectrum disorders (NMOSD) are autoimmune inflammatory diseases of the central nervous system (CNS), of which the etiology and mechanisms underlying its development are not completely understood. Although there is increasing evidence for the involvement of effector T cells in NMOSD, no data are available regarding the role of Tregs in its pathogenesis.

AIM

The aim of this study was to investigate the mRNA expression level of regulatory T cell genes in NMOSD.

METHODS

We used gene expression array and RT-PCR analysis to study Treg cell genes in NMOSD RESULTS: A distinctive Treg gene signature in the peripheral blood of NMOSD patients is described, as well as significantly decreased FoxP3 mRNA expression in the peripheral blood mononuclear cells (PBMCs) of the patients vs that in the healthy controls (HCs) (NMOSD,1.8RQ vs HC, 6.8RQ, p = 0.01).

CONCLUSIONS

The present study shows downregulation at the mRNA expression level of a Treg key transcription factor FoxP3, in NMOSD. Exploration of Tregs function and interconnections in the peripheral immune system should advance our understanding of NMOSD pathogenesis.

Pre-immunization of donor lymphocytes with GITR agonistic antibody enhances antitumor immunity in autologous hematopoietic stem cell transplantation

The lymphopenic condition following autologous hematopoietic stem cell transplantation (HSCT) enhances the proliferation of T cells by engaging tumor-associated antigens, leading to the alteration of the T-cell repertoire towards antitumor immunity. However, cure by autologous HSCT alone have rarely occurred in the clinical setting. Since tumor-reactive lymphocytes preferentially proliferate during reconstitution of the immune system, we examined whether the priming of donor lymphocytes can strengthen the antitumor effect by HSCT in a CT26 murine colon cancer model. The systemic administration of an anti-glucocorticoid-induced TNF receptor (GITR) agonistic antibody (Ab) significantly increased the number of CT26-responsive T cells but not that of auto-reactive lymphocytes in donor mice. The infusion of non-primed and GITR Ab-primed donor lymphocytes suppressed the CT26 tumor growth, and only the primed lymphocytes eliminated tumors in all the treated mice. The frequency of CT26-responsive T cells was elevated in recipient mice infused with both primed and non-primed lymphocytes until 4 weeks after transplantation, while the frequency in recipients with primed lymphocytes was markedly elevated compared with that in mice harboring non-primed lymphocytes at 2 weeks. The frequencies of regulatory T cells and myeloid-derived suppressor cells were elevated in recipient mice infused with primed and non-primed lymphocytes 2 weeks after transplantation, and returned to normal levels by week 4. The combination of autologous HSCT with pre-immunization of donor lymphocytes is a promising strategy to induce strong antitumor immunity.

Human amylin induces CD4+Foxp3+ regulatory T cells in the protection from autoimmune diabetes

Autoimmune diabetes is a disorder of immune homeostasis that leads to targeted insulin-secreting islet β cell destruction characterized by insulitis. Human amylin (hA) is an important neuroendocrine hormone co-secreted with insulin by pancreatic β cells. Here, we report hA immune-modulatory action through inducing regulatory T cells. We ex vivo-treated human peripheral blood mononuclear cells (hPBMCs) with hA for 24 h and counted CD4+Foxp3+ regulatory T cells (Treg) using flow cytometry. Diabetic status was monitored and splenic Treg were measured in non-obese diabetic (NOD) male mice. NOD mice were intraperitoneally injected once daily with hA (n = 25) or solvent for control (n = 25) for 7 months continuously. Spleen tissues were collected at the end of intervention and processed for flow cytometry and Western blot. We found a 2.9-fold (p < 0.05) increase of CD4+Foxp3+ Treg in hPBMCs treated with 10 nmol/L hA compared with negative control. Incidence of diabetes in hA-treated NOD mice decreased 44% (p = 0.045) in the 6th month and 57% (p = 0.0002) in the 7th month. Meanwhile, the hA treatment induced a 1.5-fold increase of CD4+Foxp3+ Treg from mouse splenocytes (p = 0.0013). Expression of transforming growth factor-β (TGF-β) and toll-like receptor-4 (TLR-4) were upregulated in hA-treated mice. Human amylin might protect against autoimmune diabetes via the induction of CD4+Foxp3+ Treg, which suggests a novel approach to improve autoimmune conditions.

Induction of CD4+CD25+Foxp3+ regulatory T cells by mesenchymal stem cells is associated with RUNX complex factors

Among the particular immunomodulation properties of mesenchymal stem cells (MSCs), one relies on their capacity to regulatory T cell (Treg) induction from effector T cells. Stable expression of Foxp3 has a dominant role in suppressive phenotype and stability of induced regulatory T cells (iTregs). How MSCs induce stable Foxp3 expression in iTregs remains unknown. We previously showed MSCs could enhance demethylation of Treg-specific demethylated region (TSDR) in iTregs in cell-cell contact manner (unpublished data). Here, we evaluated the possible effect of MSCs on the mRNA expression of Runx complex genes (Runx1, Runx3, and CBFB) that perch on TSDR in iTregs and play the main role in suppressive properties of Tregs, a regulatory pathway that has not yet been explored by MSCs. Also, we investigated the mRNA expression of MBD2 that promotes TSDR demethylation in Tregs. We first showed that in vitro MSC-iTreg induction was associated with strong mRNA modifications of genes involved in Runx complex. We next injected high doses of MSCs in a murine model of C57BL/6 into Balb/C allogeneic skin transplantation to prolong allograft survival. When splenocytes of grafted mice were analyzed, we realized that the Foxp3 expression was increased at day 5 and 10 post-graft merely in MSC-treated mice. Furthermore, Foxp3 mRNA expression was associated with modified Runx complex mRNA expression comparable to what was shown in in vitro studies. Hence, our data identify a possible mechanism in which MSCs convert conventional T cells to iTreg through strong modifications of mRNA of genes that are involved in Runx complex of Foxp3.

Decreased Treg-derived miR-181a and miR-155 correlated with reduced number and function of Treg cells in allergic rhinitis children

BACKGROUND

Regulatory cells (Tregs) have been proved to be deeply involved in allergic airway inflammation. This study aims to evaluate the expression of miRNA in children with AR and their association with Tregs as well as the severity of AR.

METHODS

Twenty-five AR children and 20 healthy children were enrolled in this study. The Treg-cell percentage and expression of IL-10 and TGF-β were detected by flow cytometry and enzyme-linked immunosorbent assay. The microRNA microarray analysis in purified Tregs was performed and differentially expressed microRNAs were confirmed by quantitative polymerase chain reaction (qPCR).

RESULTS

Children with AR had lower percentage of Tregs and expression of IL-10 and TGF-beta compared with control children. We found that significantly lower levels of miR-155 and miR-181a in Tregs from AR than healthy controls. Furthermore, intracellular miR-155 and miR-181a level were positively correlated with percentage of Tregs and expression of IL-10 and TGF-beta. Similarly, total nasal severity scores (TNSS) were found to be negatively correlated with miR-155 and miR-181a levels.

CONCLUSION

Decreased Treg-derived miR-181a and miR-155 were correlated with reduced number and function of Tregs in AR children. The intracellular miR-155 and miR-181a levels may serve as predictors of disease severity in childhood AR.

Stem cells from human exfoliated deciduous teeth correct the immune imbalance of allergic rhinitis via Treg cells in vivo and in vitro

Background

Several studies have demonstrated that mesenchymal stem cells can ameliorate the inflammation of allergic rhinitis (AR) and correct the Th1/Th2 immune imbalance.

Methods

This study was performed to explore the immunomodulation properties of stem cells from human exfoliated deciduous teeth (SHEDs) in the treatment of AR in vivo and in vitro. BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injection, and then SHEDs or bone marrow mesenchymal stem cells (BMMSCs) were injected intravenously before challenge. We evaluated nasal symptoms, inflammatory infiltration of nasal mucosa, immunoglobulin secretion, cytokine production, and mRNA expression in the spleen. In addition, peripheral blood mononuclear cells (PBMCs) from AR patients were cultured with SHEDs or BMMSCs in the presence of phytohemagglutinin (PHA). PBMCs cultured alone with or without PHA served as controls. After 3 days of culture, we examined the effect of SHEDs on T lymphocyte proliferation, cytokine secretion, and the proportion of Foxp3⁺ Treg cells via flow cytometry. Finally, to determine the role of soluble factors (TGF-β₁, PGE₂) in the immunomodulatory mechanism, a cytokine neutralization assay was performed.

Results

Nasal symptoms and inflammatory infiltration were significantly reduced after SHED administration. The OVA-specific IgE and IgG₁ levels in serum were significantly decreased, and the increased IL-4, IL-5, IL-13, and IL-17A levels in the spleen after OVA challenge were markedly downregulated, while the level of IFN-γ was upregulated by SHED administration. The mRNA expression levels also changed correspondingly. SHEDs significantly inhibited the proliferation of T lymphocytes; increased the levels of IFN-γ, IL-10, PGE₂, and TGF-β₁; decreased the levels of IL-4 and IL-17A; and induced the expansion of Treg cells in the coculture system. The neutralization of TGF-β₁ partly relieved the immunosuppression of SHEDs, but blocking PGE₂ did not. In addition, SHEDs were superior to BMMSCs in inhibiting the Th2 immune response in vivo and inducing the expansion of Treg cells in vitro.

Conclusion

These results suggest that SHEDs could correct the CD4⁺ T cell immune imbalance via Treg cells and may be potential therapeutic agents for the treatment of allergic diseases, such as AR, in the future.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1134-z) contains supplementary material, which is available to authorized users.

Novel strains of Bacteroides fragilis and Bacteroides ovatus alleviate the LPS-induced inflammation in mice

Lipopolysaccharide (LPS) can promote the expression of pro-inflammatory cytokines, damage the tight junction of epithelial walls, and thereby lead to chronic low-grade intestinal inflammatory disorders. Evidences of many beneficial functions from Bacteroides strains suggest their intervention capabilities in LPS-induced inflammation. In the present study, both healthy and LPS-treated mice were consistently treated with Bacteroides strains for 5 days. The intestinal microbiota alteration, epithelial permeability, cytokine expression, and autoimmune and innate immune responses were analyzed. B. fragilis HCK-B3 and B. ovatus ELH-B2 from our laboratory collection were demonstrated to assist intestinal equilibrium by maintaining the diversity of gut microbiota and relieve LPS-induced inflammation by either modulating cytokine production or restoring the Treg/Th-17 balance. Our research indicated that the Bacteroides strains with capabilities of alleviating inflammation have the potential as therapeutics to prevent intestinal inflammatory disorders and provided scientific supports for discovering next-generation probiotics.

Early injection of human adipose tissue-derived mesenchymal stem cell after inflammation ameliorates dextran sulfate sodium-induced colitis in mice through the induction of M2 macrophages and regulatory T cells

Inflammatory bowel diseases (IBDs) are sometimes refractory to current therapy or associated with severe adverse events during immunosuppressive therapy; thus, new therapies are urgently needed. Recently, mesenchymal stem cells (MSCs) have attracted attention based on their multitude of functions including anti-inflammatory effects. However, proper timing of MSC therapy and the mechanisms underlying the therapeutic effects of MSCs on colitis are not fully elucidated. Human adipose tissue-derived mesenchymal stem cells (hAdMSCs; 1 × 10⁶) were administrated via the tail vein on day 3 (early) or 11 (delayed) using a 7-day dextran sulfate sodium (DSS)-induced mouse model of colitis. The effects were evaluated based on colon length, disease activity index (DAI) and histological score. Cytokine-encoding mRNA levels T cells and macrophages were evaluated by real-time PCR and flow cytometry. Regarding the timing of administration, early (day 3) injection significantly ameliorated DSS-induced colitis in terms of both DAI and histological score, compared to those parameters with delayed (day 11) injection. With early cell injection, the tissue mRNA levels of anti-inflammatory cytokine genes (Il10, Tgfb) increased, whereas those of inflammatory cytokine genes (Il6, Tnfa and Il17a) decreased significantly. Regarding the associated mechanism, hAdMSCs suppressed T cell proliferation and activation in vitro, increased the number of regulatory T cells in vivo and changed the polarity of macrophages (into the anti-inflammatory M2 phenotype) in vitro. Timing of injection is critical for the effective therapeutic effects of hAdMSCs. Furthermore, part of the associated mechanism includes T cell activation and expansion and altered macrophage polarization.

Multi-faceted inhibition of dendritic cell function by CD4+Foxp3+ regulatory T cells

CTLA-4 is required for CD4⁺Foxp3⁺ regulatory T (Treg) cell function, but its mode of action remains incompletely defined. Herein we generated Ctla-4^ex2fl/flFoxp3-Cre mice with Treg cells exclusively expressing a naturally occurring, ligand-independent isoform of CTLA-4 (liCTLA-4) that cannot interact with the costimulatory molecules CD80 and CD86. The mice did not exhibit any signs of effector T cell activation early in life, however, at 6 months of age they exhibited excessive T cell activation and inflammation in lungs. In contrast, mice with Treg cells completely lacking CTLA-4 developed lymphoproliferative disease characterized by multi-organ inflammation early in life. In vitro, Treg cells exclusively expressing liCTLA-4 inhibited CD80 and CD86 expression on dendritic cells (DC). Conversely, Treg cells required the extra-cellular part of CTLA-4 to up-regulate expression of the co-inhibitory molecule PD-L2 on DCs. Transcriptomic analysis of suppressed DCs revealed that Treg cells induced a specific immunosuppressive program in DCs.

Effect of regulatory T cells on the efficacy of the fatty acid-binding protein vaccine against Schistosoma japonicum

Schistosomiasis is one of the most devastating parasitic diseases, making it imperative to develop efficient vaccines to control the causative flatworms called schistosomes. Regulatory T cells (Tregs) and the Th1 immune response have been implicated in the effectiveness of vaccines to control schistosomiasis, but the mechanisms underlying their effects are unclear. In this study, we evaluated the role of Tregs on the efficacy of the 14 kDa FABP (fatty acid-binding protein) vaccine against Schistosoma japonicum. BALB/c female mice were randomly divided into five groups: an uninfected group, infected control group, anti-CD25 monoclonal antibody (anti-CD25 mAb) group, FABP group, and combined anti-CD25 mAb and FABP group. Compared with FABP alone, a combined treatment with FABP and anti-CD25 mAb increased the rate of S. japonicum inhibition in mice from 30.3 to 56.08% and decreased the number of eggs per gram of liver. Compared with that of the infected control group, the percentage of Tregs in the spleen decreased significantly after single or combined treatment with FABP and anti-CD25 mAb, while it increased gradually in the anti-CD25 mAb group. Further, the secretion of Th1 cytokines, IFN-γ, and IL-2 increased in splenocytes in the anti-CD25 mAb group. Our results indicate that anti-CD25 mAb partially blocks Tregs and concomitantly enhances the Th1 type immune response, thereby enhancing the protective effect of the FABP vaccine.

Isolation of Human Regulatory T Lymphocytes by Fluorescence-Activated Cell Sorting

Regulatory T cells (Tregs) are a population of lymphocytes that exerts suppressive effects upon the immune system. In human peripheral blood, the major population of T lymphocytes with suppressive capacity are defined by expression of the T cell co-receptor CD4 and the interleukin-2 receptor α-chain (CD25), combined with minimal expression of the interleukin-7 receptor α subunit (CD127). We begin by outlining the method for isolating peripheral blood mononuclear cells (PBMCs) from human blood by centrifugation of whole blood overlayed on a hydrophilic polysaccharide, with an additional erythrocyte lysis step. The protocol that follows utilizes Fluorescence-Activated Cell Sorting (FACS) for the isolation of this CD4⁺CD25⁺CD127^lo population of regulatory T cells, with high yield and purity, from immunostained PBMCs. Prior to FACS isolation, this protocol exploits magnetic immunoselection for pre-enrichment of CD25⁺ PBMC, which reduces the duration of the subsequent FACS isolation.

Measuring CTLA-4-Dependent Suppressive Function in Regulatory T Cells

Regulatory T cells (Treg) have a central role in controlling the activation of self-reactive T cells and maintaining peripheral tolerance in our body. Many effector mechanisms for Treg function have been described including a role for the protein CTLA-4 which is constitutively expressed by these cells. Despite its importance, there is currently little consensus in the methods and protocols for studying CTLA-4 function, which is partially due to debate over CTLA-4 function itself. In this chapter, we outline protocols used in our lab to study CTLA-4 function, which have been generated based on the observation that CTLA-4 acts to physically remove and degrade its ligands expressed by antigen presenting cells. Accordingly, we provide protocols for isolation of human monocytes and their differentiation into dendritic cells (DC), purification of conventional and regulatory T-cell populations, and the assembly of CTLA-4-dependent Treg suppression assays. We hope that this will offer a reliable platform for dissecting the biology of CTLA-4 on Treg and for testing reagents aimed at modulating CTLA-4 function. Such assays are increasingly vital for the study of immune function in both healthy individuals and patients with a variety of autoimmune and immune dysregulation syndromes.

A Comparative Evaluation of Regulatory T Cells Profile among Acute and Chronic Cutaneous Leishmaniasis Using Flow Cytometry

BACKGROUND

Cutaneous leishmaniasis (CL) is described as a major health problem in many countries of the world. Regulatory T cells (Tregs) are characterized as one of immunologic indexes. One of the best methods to determine of Tregs percentage is flow cytometry. The aim of this study was determination of the role of Tregs profile among acute and chronic forms of human CL using flow cytometry analysis.

METHODS

This study was conducted on 24 patients referred to Laboratory of Leishmaniasis, Tehran University of Medical Sciences, Tehran, Iran with acute and 14 patients with chronic phases of CL as well as 15 healthy individuals as control group in 2015-2016. After microscopic examination, 2 ml of peripheral blood samples were collected for determining percentage of CD₄ ⁺ CD₂₅ ⁺ CD₁₂₇ low Tregs by using flow cytometry method.

RESULTS

Using flow cytometry analysis, the average percentage of Tregs were calculated 5.73, 6.71 and 6.61 for acute, chronic and healthy individuals, respectively. With SPSS software and Scheffe multiple comparison tests, the differences within in these groups are statistically significant (P=0.04) and between the acute and chronic group, there was marginally significant with approximately 91% of confidence level (P=0.088).

CONCLUSION

Marginally differences were found significantly among averages of Regulatory T cells, acute and chronic phases of CL. Further comprehensive studies can be needed to verify the role of Tregs in both phases of CL cases.

Thymol as a reciprocal regulator of T cell differentiation: Promotion of regulatory T cells and suppression of Th1/Th17 cells

Regulatory T cells (Tregs) are critical for maintaining immune response and enhancing their differentiation has therapeutic implications for autoimmune diseases. In this study, we investigated the effects of thymol a well-known monoterpene from Thyme on differentiation and function of Tregs. In vitro generation of Tregs from purified naïve CD4⁺CD25^- T cells in the presence of thymol was carried out. Suppressor activity of generated Tregs was examined by changes in the proliferation of CFSE-labeled conventional T cells. Thymol promotes differentiation of naïve CD4⁺CD25^- T cells to CD4⁺CD25⁺Foxp3⁺ Tregs [66.9-71.8% vs. control (47%)] and increased intensity of Foxp3 expression on Tregs (p < 0.01). In functional assay, an increased immune suppression by thymol-induced Tregs (≈2.5 times of untreated Tregs) was detected. For in vivo study, thymol was intraperitoneally administered to ovalbumin (Ova)-immunized mice. Flow cytometry assessment of spleens from thymol-treated Ova-immunized mice showed increased number of CD4⁺ Foxp3⁺ Tregs (>8%, p < 0.01(and decreased levels of CD4⁺T-bet⁺ Th1 and CD4⁺RORγt⁺ Th17 cells resulted in significant decreased Th1/Treg and Th17/Treg ratios. In ex vivo Ova challenge of splenocytes from thymol-treated Ova-immunized mice, similarly higher levels of CD4⁺ Foxp3⁺ Tregs, and also elevated TGF-β expression in CD4⁺Foxp3⁺ population (48.1% vs. 18.9% in untreated Ova-immunized group) and reduced IFN-γ-producing CD4⁺T-bet⁺ T cells and IL-17-producing CD4⁺RORγt⁺ T cells were detected. This led to marked decreased ratios of IFNγ/TGF-β and IL-17/TGF-β expressions. In conclusion, this study revealed thymol as a compound with enhancing effects on Treg differentiation and function, which may have potential benefits in treatment of immune-mediated diseases with Th1/Th17 over-activation.

IL-35 interferes with splenic T cells in a clinical and experimental model of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening critical care syndrome with uncontrolled inflammation that is a central issue. Its main characteristic is inflammatory mediators and cytokines as well as agglutinating chemokines that injure target cells. Interleukin (IL)-35 is a newly identified IL-12 cytokine family member with structural similarities to other IL-12, IL-23, and IL-27 cytokines but unique immunological functions. How IL-35 functions in ARDS is unclear. The purpose of our study was to determine what role IL-35 played in the development of ARDS. Here we found serum IL-35 concentrations were significantly elevated in patients with ARDS relative to healthy people. Moreover, we established a mouse model of lipopolysaccharide- and cecal ligation and puncture-induced ARDS treated with neutralizing antibodies (anti-IL-35 Ebi3 or anti-IL-35 P35); the results showed that lung injury occurred more often than in untreated models and the inflammatory cytokines CXCL-1, tumor necrosis factor alpha, IL-6, and IL-17A increased significantly after neutralizing antibody treatment in bronchoalveolar lavage fluid and serum. Therefore IL-35 can protect against the development of ARDS. Even more interesting in our study was that we discovered IL-35 expression differed between lung and spleen across different ARDS models, which further demonstrated that the spleen likely has an important role in extrapulmonary ARDS model only, improving the ratio of CD4⁺/CD4⁺CD25⁺Foxp3⁺(Tregs). Meanwhile in our clinical work, we also found that the concentration of IL-35 and the ratio of CD4⁺/Treg in the serum are higher and the mortality is lower than those with the spleen deficiency in patients with extrapulmonary ARDS. Therefore, IL-35 is protective in ARDS by promoting the ratio of splenic CD4⁺/Tregs in extrapulmonary ARDS, and as such, may be a therapeutic target.

CCL1 is a major regulatory T cell attracting factor in human breast cancer

Background

Regulatory T cells (Treg) suppress cytotoxic T cell anti-tumoral immune responses and thereby promote tumor progression. Prevention of intratumoral Treg accumulation by inhibition of their migration to the tumor microenvironment is a promising therapeutic strategy. The aim of this study was to identify the role of the two major Treg-attracting chemokines CCL1 and CCL22 in human breast cancer.

Methods

One hundred ninety-nine tissue samples of patients with invasive breast cancer were stained for CCL1 and CCL22 by immunohistochemistry. Chemokine expression and tumor infiltration by regulatory T cells, determined by expression of the transcription factor FoxP3, were quantified and their correlation to clinical features was statistically analyzed.

Results

Both CCL1 and CCL22 were expressed in most breast cancer tissues. CCL1 was significantly over-expressed in invasive breast cancer as compared to normal breast tissue. CCL1, but surprisingly not CCL22, showed a significant correlation with the number of tumor-infiltrating FoxP3+ Treg (p< 0.001). High numbers of intratumoral CCL1 expressing cells were related to high grade tumors (G4) and a positive estrogen receptor (ER) status whereas high CCL22 expression was generally seen in lower grade tumors. The median survival of 88 patients with high intratumoral CCL1 expression was 37 months compared to 50 months for the 87 patients with low CCL1 levels, this trend was however not statistically significant.

Conclusions

We found a high expression of CCL1 in human breast cancer. CCL1 significantly correlated with the infiltration of immunosuppressive FoxP3+ Treg, that are known to negatively affect survival. Thus, CCL1 may serve as prognostic marker and novel therapeutic target in breast cancer.

Immunosuppressive therapy influences the accelerated age-dependent T-helper cell differentiation in systemic lupus erythematosus remission patients

Background

CD4⁺ T cells are of great importance in the pathogenesis of systemic lupus erythematosus (SLE), as an imbalance between CD4⁺ regulatory T cells (Tregs) and CD4⁺ responder T cells (Tresps) causes flares of active disease in SLE patients. In this study, we aimed to find the role of aberrant Treg/Tresp cell differentiation for maintaining Treg/Tresp cell balance and Treg functionality.

Methods

To determine differences in the differentiation of Tregs/Tresps we calculated the percentages of CD45RA⁺CD31⁺ recent thymic emigrant (RTE) Tregs/Tresps and CD45RA⁺CD31⁻ mature naive (MN) Tregs/Tresps, as well as CD45RA⁻CD31⁺ and CD45RA⁻CD31⁻ memory Tregs/Tresps (CD31⁺ and CD31⁻ memory Tregs/Tresps) within the total Treg/Tresp pool of 78 SLE remission patients compared with 94 healthy controls of different ages. The proliferation capacity of each Treg/Tresp subset was determined by staining the cells with anti-Ki67 monoclonal antibodies. Differences in the autologous or allogeneic Treg function between SLE remission patients and healthy controls were determined using suppression assays.

Results

With age, we found an increased differentiation of RTE Tregs via CD31⁺ memory Tregs and of RTE Tresps via MN Tresps into CD31⁻ memory Tregs/Tresp in healthy volunteers. This opposite differentiation of RTE Tregs and Tresps was associated with an age-dependent increase in the suppressive activity of both naive and memory Tregs. SLE patients showed similar age-dependent Treg cell differentiation. However, in these patients RTE Tresps differentiated increasingly via CD31⁺ memory Tresps, whereby CD31⁻ memory Tresps arose that were much more difficult to inhibit for Tregs than those that emerged through differentiation via MN Tresps. Consequently, the increase in the suppressive activity of Tregs with age could not be maintained in SLE patients. Testing the Tregs of healthy volunteers and SLE patients with autologous and nonautologous Tresps revealed that the significantly decreased Treg function in SLE patients was not exclusively attributed to an age-dependent diminished sensitivity of the Tresps for Treg suppression. The immunosuppressive therapy reduced the accelerated age-dependent Tresp cell proliferation to normal levels, but simultaneously inhibited Treg cell proliferation below normal levels.

Conclusions

Our data reveal that the currently used immunosuppressive therapy has a favorable effect on the differentiation and proliferation of Tresps but has a rather unfavorable effect on the proliferation of Tregs. Newer substances with more specific effects on the immune system would be desirable.

Electronic supplementary material

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Expression of TLR4 and its effect on Treg cells in early pregnancy decidual stromal cells after lipopolysaccharide treating

OBJECTIVE

To investigate the expression of TLR4 in human early pregnancy decidual stromal cells (DSCs) induced by lipopolysaccharide (LPS) and its effect on the peripheral blood regulatory T (Treg) cells subgroup in women of childbearing age.

METHOD

Isolating and cultivating normal human early pregnancy DSCs followed by treatment with 0, 25, 50, 100 and 200 ng/ml LPS, and the expression level of TLR4 mRNA was detected by RT-PCR. After 3 or 4 generation we divide the DSCs into 5 groups: ①Control group: Cultivation of peripheral blood lymphocyte (PBLC); ②Co-cultivation group: Co-cultivation of PBLC and DSCs; ③LPS stimulation group: PBLC + DSCs + LPS; ④PDTC blocking-up group: PBLC + DSCs + LPS + PDTC; ⑤TLR4 blocking-up group: PBLC + DSCs + LPS + TLR4mAb. In ①-④ groups, western blot was used to detect the expression of inhibitory factor-κB (IκB-α) protein and RT-PCR was used to detect the expression of FoxP3 mRNA. In ①-⑤ groups, flow cytometry was applied to detect the percentage of Treg cells subgroup.

RESULTS

The purity of primary cultured DSCs was more than 95%. RT-PCR results showed that the expression level of TLR4 mRNA increased gradually with the augment of LPS concentration. Western blot and RT-PCR showed that the expression of IκBα protein and FoxP3 mRNA in the other 3 groups was significantly higher than that in the control group (P <  0.05), and the expression of IκBα protein and FoxP3 mRNA in LPS stimulation group was lower than that in the co-cultivation group (P <  0.05). Compared with the LPS stimulation group, the expression of IκBα protein and FoxP3 mRNA in PDTC blocking-up group was higher than that in the LPS stimulation group (P <  0.05), but still lower than the co-cultivation group (P <  0.05). The proportion of Treg cells in the other 4 groups detected by flow cytometry was significantly higher than that in the control group (P <  0.05). Compared with the co-cultivation group, the Treg cells ratio of the LPS stimulation group was significantly decreased (P <  0.05). The proportions of Treg cells in PDTC blocking-up group and TLR4 blocking-up group were higher than that in the LPS stimulation group, but still lower than that in the co-cultivation group (P <  0.05). There was no significant difference between the PDTC blocking-up group and the TLR4 blocking-up group (P > 0.05).

CONCLUSION

Human early pregnancy DSCs can promote the differentiation of Treg cells. LPS can stimulate the expression of TLR4 in early pregnancy DSCs and decrease the proportion of Treg cells in PBLC, with NF-κB signaling pathway being the potential underlying mechanisms.

Mechanisms of Oral Tolerance

Oral tolerance is a state of systemic unresponsiveness that is the default response to food antigens in the gastrointestinal tract, although immune tolerance can also be induced by other routes, such as the skin or inhalation. Antigen can be acquired directly by intestinal phagocytes, or pass through enterocytes or goblet cell-associated passages prior to capture by dendritic cells (DCs) in the lamina propria. Mucin from goblet cells acts on DCs to render them more tolerogenic. A subset of regulatory DCs expressing CD103 is responsible for delivery of antigen to the draining lymph node and induction of Tregs. These DCs also imprint gastrointestinal homing capacity, allowing the recently primed Tregs to home back to the lamina propria where they interact with macrophages that produce IL-10 and expand. Tregs induced by dietary antigen include Foxp3⁺ Tregs and Foxp3^- Tregs. In addition to Tregs, T cell anergy can also contribute to oral tolerance. The microbiota plays a key role in the development of oral tolerance, through regulation of macrophages and innate lymphoid cells that contribute to the regulatory phenotype of gastrointestinal dendritic cells. Absence of microbiota is associated with a susceptibility to food allergy, while presence of Clostridia strains can suppress development of food allergy through enhancement of Tregs and intestinal barrier function. It is not clear if feeding of antigens can also induce true immune tolerance after a memory immune response has been generated, but mechanistic studies of oral immunotherapy trials demonstrate shared pathways in oral tolerance and oral immunotherapy, with a role for Tregs and anergy. An important role for IgA and IgG antibodies in development of immune tolerance is also supported by studies of oral tolerance in humans. The elucidation of key pathways in oral tolerance could identify new strategies to increase efficacy of immunotherapy treatments for food allergy.

Stem cells repurpose proliferation to contain a breach in their niche barrier

Adult stem cells are responsible for life-long tissue maintenance. They reside in and interact with specialized tissue microenvironments (niches). Using murine hair follicle as a model, we show that when junctional perturbations in the niche disrupt barrier function, adjacent stem cells dramatically change their transcriptome independent of bacterial invasion and become capable of directly signaling to and recruiting immune cells. Additionally, these stem cells elevate cell cycle transcripts which reduce their quiescence threshold, enabling them to selectively proliferate within this microenvironment of immune distress cues. However, rather than mobilizing to fuel new tissue regeneration, these ectopically proliferative stem cells remain within their niche to contain the breach. Together, our findings expose a potential communication relay system that operates from the niche to the stem cells to the immune system and back. The repurposing of proliferation by these stem cells patch the breached barrier, stoke the immune response and restore niche integrity.